Control for carburetor idling systems



April 25, 1939.

A, c. MACBETH GONTRL FOR CAHBURETOR IDLING SYSTEMS Fiied Jan. 1e, 1957 INVENTOR. C, M Bef v ATToRNEYl Patented Apr. 25, 1939 UNITED sTATEs PATENT OFFICE CONTROL FOR CARBURETOR IDLING I SYSTEMS 4 Claims.

This invention relates to carburetors and particularly is directed to a governing device therefor acting to automatically control the fuel supply delivered for idling purposes to the combustion chambers of an internal combustion engine.

With the purpose of clarifying the objective aims of the present invention it is believed advantageous to initially set forth the principal disadvantage of the idling jet arrangement as the same operates in the conventional carburetor. This fuel supply for idling purposes is a ne jet of relatively raw gasoline drawn through a flow passage independent of the Venturi throat of the carburetor under the influence oi motor vacuum developing in response to a closing of the butterfly throttle plate. It is the fact that control is entirely dependent on the butterfly valve which results in drawing the rich idling mixture into the intake manifold and thence to the combustion chambers of the motor not only under idling speeds but also under higher coasting speeds, the greater vacuumatic pull, moreover, which develops at the higher engine speeds during coasting periods drawing a proportionately larger vol- )5 ume of the rich idling mixture into the engine to constitute a major cause of crank-case dilution as well as gasoline waste.

The present invention has as its principal object they provision of means by which the car- 30 buretor, during such coasting periods of higher revolution engine speed, supplies air through said idling passage rather than the relatively raw gasoline necessary to a correct idling mixture. This object, together with further and more par- ;m ticular objects and advantages, will be apparent in the course of the following detailed description and claims, the invention consisting in the novel construction, adaptation, and combination of parts hereinafter described and claimed. 40 In the drawing:

Figure l is an elevational view illustrating structure embodying the present invention as applied to the carburetor of an internal-combustion engine, the electric circuit therefor being shown 5 somewhat schematic and the fragmentarily illustrated carburetor and intake manifold represented in section.

Fig. 2 is a longitudinal vertical section taken through the idling needle valve assembly repre- 50 sented in the preceding view; and

Fig. 3 is a transverse vertical section on the line 3-3 of Fig. 2.

According to conventional practice, gasoline drawn for idling purposes into the intake mani- 55 fold of the engine is by-passed about the venturi of the carburetor through a duct which leads from the gasoline supply to th'e outlet barrel of the carburetor. Provided in this duct is an idling jet and communicating with the duct is an airsupply port generally exposed to the space which I lies externally of the Venturi tube, this space communicating with the main air well of the carburetor. An idling needle valve is provided which acts to regulate the effective opening of the air port and as now applied provides a xed idling 10 mixture as between the air drawn through the air port and the gasoline drawn through the idling jet, a mixture which necessarily is rich to carry combustion at minimum motor speed. In the drawing the carburetor is denoted generally by the numeral 5 and the intake manifold to which the iianged outlet barrel 6 of the carburetor is attached is indicated by 1. 8 represents the bypassage for the idling mixture and 9 the port thereto leading from an air space I0 which sur- 20 rounds the Venturi tube II and communicates with the carburetor air-well I2. For simplicity in illustration, the jet nozzle for the gasoline is not shown in the passage 8. I3 designates the discharge tube from the main gasoline jet nozzle, I 4 the supplemental jet, and I5 the butterfly valve which is controlled by the accelerator pedal. Each of the described parts are or may be of Well known or suitable construction.

According to the illustrated preferred embodiment of the present invention, the needle valve by which the idling mixture is governed is formed as the axial prolongation 20 of an armature 2|, said armature being received in the cylinder of a solenoid 22 and being retracted under the mag- 35 netic attraction of the solenoid in opposition to a spring 23 which surrounds a pin extension 24 of the armature. The armature-receiving cylinder is indicated as being internally threaded at its rear end and externally threadedat its in- 4.0 ner end, the latter to receive a cap 25 having a valve-fitting tubular extension 25 on which are external threads to permit introduction of the extension in the Wall of the carburetor in position to locate the needle valve in operative relation to the air port 9. The armature, de-energzed, governs the travel of the needle valve in the port-closing movement of the latter by abutting the inner face of the cap under the influence of spring 23, thread regulation of said extended portion 25' of the cap in the wall of the carburetor allowing the needle valve to be adjusted for a correct idling mixture. A lock nut for xing said adjustment is indicated at 25, and 26 designates a center-bored gland fltting the opposite internally-threaded end of the solenoid cylinder for adjusting the tension of spring 23. A lock nut for the gland is represented at 21.

For wiring the solenoid in an electric circuit in cluding the generator 30 and ammeter 3 I, binding posts 28 are provided.

In its operation, the needle valve, at idling speeds of the motor during which the charging of the generator is cut out, is maintained at its predetermined setting to obtain the required rich mixture necessary for idling. By the present invention the higher motor R. P. M. sufficient to pass an electric charge from the generator through the solenoid 22 magnetically influences the armature such as to retract the needle valve and fully open the port 9. A removal of the operators foot from the accelerator pedal under such higher motor R. P. M., the needle valve being open, concentrates substantially the entire vacuumatic pull towards drawing air rather than a raw fuel mixture into the combustion chambers of the motor. I nd a most effective charging rate at which to cut out the rich idling mixture is in excess of 5 amperes, the arrangement being readily set to this or a lower charging rate by adjusting the spring tension through the instrumentality of the gland 2B.

I wish it to be understood that no limitations are to be implied from the foregoing description of my illustrated embodiment excepting as the same may necessarily be employed in the following claims to distinguish from the prior state of the art. Substantially all carburetors, both updraft and down-draft, operate by the principle described. In the few exceptions where the op- Ieration is reversed, it is obvious to alter the present disclosure accordingly.

What I claim is:

l. In an internal combustion engine with which is employed a generator driven by said engine, the combination therewith and with a fuel-feeding carburetor characterized` by the provision of a by-pass through which fuel and air are drawn under engine vacuum following throttle-valve closure, generator-governed means acting entirely in response to engine speed for decreasing the effective volume of air available through saidA bypass at an idling motor speed and increasing said available volume of air at a predetermined engine speed in excess of said idling speed.

2. In an internal combustion engine with which is employed a generator driven by said engine, the combination therewith and with a fuel-feeding carburetor characterized by the provision of a by-pass through which fuel and air are drawn under engine vacuum. following throttle-valve closure, means operating independently of said throttle valve and comprising a generator-governed solenoid and devices associated with said solenoid for governing the carburetion action of the carburetor during idling speeds of the engine and engine speeds exceeding said idling speeds to decrease and increase, in the respective instances, the effective volume of air available through said by-pass.

3. In an internal combustion engine with which is employed a generator driven by said engine, the combination therewith and with a fuel-feeding carburetor characterized by the provision of a passage through which a :tine jet of fuel and air are supplied to the engine following a closing of the carburetor throttle valve, generator governed means by which a rich idling mixture is supplied through said passage, during idling speeds and a lean mixture supplied through the passage during speeds of the engine exceeding said idling speeds, said means being adjustable for regulating the same in relation to engine speed.

4. Mechanism for use' with a carburetor of the character providing a fuel-feeding by-pass having an air-port leading thereto for regulating the carburetor to restrict the effective capacity of the air port during idling speeds of an engine with which the carburetor is used and increase said capacity during periods at which the engine is operating above said idling speeds, said mechanism comprising a valve for the air port, and devices operating to provide a magnetic circuit including said valve, said circuit-forming devices being governed entirely by the speed of the engine to control the valvemovement.

ALBERT C. MACBETH. 

